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Re: Location Narrowed For Permian/Triassic Impact



> http://www.nytimes.com/2003/12/16/science/16EXTI.html
> <snippage>
> If scientists become convinced of the meteor evidence, that would 
> reopen
> the debate on whether meteors can not only cause extinctions, but 
> also set
> off huge volcanic eruptions thousands of miles away, because the 
> Siberian
> eruptions coincide exactly with the Permian-Triassic extinction.


"Coincide exactly"?
I wonder how the researchers managed to achieve that level of
geochronological precision at for an event that occured 250 million years
ago, considering that radiometrically-dated Pleistocene artifacts
("yesterday", geologically-speaking) typically have at least a +/- 500
year error bar.



> The
> dinosaur extinction 65 million years ago coincided with similarly
> extensive eruptions in India. Each type of event is rare, and two
> coincidences strike some scientists as highly unlikely.
> ...

 
Some random comments about  the "combined volcano-impact" extinction
hypothesis:

1) At 65 mya, India was not antipodal to Chicxulub  (it was in the
general area, but in this case it won't git ya a cigar).

2) Worse yet (for the "Impacts Cause Volcanism" hypothesis), the Deccan
Traps began erupting *before* the K-T impact event.

3) A test of the "Volcanism Causes Mass Extinctions" hypothesis:  The
huge Miocene Columbia River plateau basalt flows (CRB) are not correlated
to any recognizable mass extinction (nor are the flows correlated to any
recognizable local extinctions).

4) The epicenters of these flows (both the CRB and Deccan) were, most of
the time, safe places for terrestrial vertebrates to live.  The
sedimentary interbeds between the basalts contain a rich fossil
vertebrate fauna and fossil flora.  For the CRB interbeds, Rodentia,
Carnivora and Ungulata are well represented.  The Deccan sedimentary
interbeds contain dinosaurs, meaning that Dinosauria lived for quite some
time after the first Deccan flows had erupted.  The taxon lived on long
enough to see the local ecosystem restore itself (multiple times), and to
see a soil/vegetative layer develop on the tops of the basalt flows.

<pb>
--






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